Astronaut M2
Posted January 13, 2020 - 4:20am
In reply to Hi, may I know what means the by Endriu1981
The delta mark (triangle) means a transitionary period starting late 1963 and ending early 1964, It was a change in the lip of the bezel that the dial rests against when the movement is installed in the bezel, The change was to a much larger bezel lip which prevented the dial from dishing more and pushing past the lip...
http://accutronfacts.freeforums.net/thread/354/delta-triangle-cases-finally-means